The invention concerns a heat exchanger with liquid circulation, particularly a radiator which is a part of a cooling circuit for an internal combustion engine of an automobile.
It more precisely concerns a heat exchanger of the type comprising a cluster of tubes in which the liquid circulates, at least one collector reservoir mounted at one end of the cluster, an expansion chamber in communication with the bottom of the collector reservoir and a liquid degasification passage connecting the collector reservoir to the expansion chamber, the collector reservoir including within it at least one transverse wall situated above the level of the degasification passage.
A heat exchanger of this type is known particularly from French Patent application No. 81 19 272, published as No. 2 514 479, in the name of this applicant, corresponding to U.S. Pat. No. 4,491,174. This known heat exchanger comprises a cluster of tubes in which the liquid circulates, a first collector reservoir mounted at one end of the cluster, a second collector reservoir mounted at the other end of the cluster, an expansion chamber communicating with the second collector reservoir at the bottom and a liquid degasification passage connecting the first collector reservoir through the tube cluster to the expansion chamber, the second collector reservoir comprising a transverse wall, in this case a transverse partition, situated above the level of the liquid degasification passage and allowing the fluid to circulate in a U-shaped path through the tubes of the cluster.
In this known heat exchanger, the purpose of the degasification passage is to evacuate the air bubbles which are formed and are captured and held in the coolant liquid toward the expansion chamber, particularly the air bubbles which may be present in the first collector reservoir.
In fact, it is known that such bubbles which circulate in the cooling circuit of the engine have a tendency to gather together at certain points around the cylinder head of the engine while causing the risk of the appearance of "hot points" which can eventually deteriorate certain parts of the engine because of insufficient cooling.
In the heat exchanger which is known from the aforementioned French Patent application, the transverse wall is actually a transverse partition which is provided in the second collector reservoir, dividing this reservoir into two compartments, which are a bottom compartment and a top compartment, and which thus forces the liquid to circulate in one direction from the second collector reservoir toward the first collector reservoir and in the other direction from the first collector reservoir toward the second collector reservoir. The liquid thus circulates in the cluster of tubes following a U-shaped circuit path, which is called a "bi-circuit".
However, this known exchanger presents one major drawback, given that the air bubbles have a tendency to regroup and consolidate under said transverse partition in the bottom compartment of the second collector reservoir, without being able to be evacuated correctly toward the expansion chamber.
In addition to that, the realization of this degasification passage is relatively complex because it requires particularly a bent tube of which one end must be sealed communication with the expansion chamber.
In addition, it is known, in accordance with French Patent application No. 81 19179, published as No. 2 514 484, in the name of this applicant, to provide a degasification passage between a collector reservoir and an expansion chamber which communicate with each other and are situated at one end of a cluster of tubes. Nonetheless, this already disclosed passage does not efficiently solve the problem of the degasification of the collector reservoir situated at the other end of the cluster of tubes.